FOCUS O N M OLECULAR I MAGING

Noninvasive molecular imaging of dynamic processes has benefited tremendously from the use of reporter genes. These genes encode for proteins that emit light, bind radiolabeled probes,or,ascoveredinthis review,modulateMRIcontrast. Reportergenesplayapivotal role inmonitoring celltrafficking, gene replacement therapy, protein‐protein interactions, neuronal plasticity, and embryonic development. Several strategies exist for generating MRI contrast: using enzyme-catalyzed chemical modification of metal-based contrast agents or (phosphorus) metabolites, iron-binding and iron-storage proteins to accumulate iron as a contrast agent, and artificial proteins for imaging based on chemical exchange saturation transfer. MRI reporter genes have the advantage that the specific signal can be coregistered with soft-tissue anatomy and functional tissue information and have, therefore, become an active and growing area of scientific interest.